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-"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
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- Copyright 2014 Lennart Poettering
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--->
-
-<refentry id="sd_event_add_time" conditional="ENABLE_KDBUS">
-
- <refentryinfo>
- <title>sd_event_add_time</title>
- <productname>systemd</productname>
-
- <authorgroup>
- <author>
- <contrib>Developer</contrib>
- <firstname>Lennart</firstname>
- <surname>Poettering</surname>
- <email>lennart@poettering.net</email>
- </author>
- </authorgroup>
- </refentryinfo>
-
- <refmeta>
- <refentrytitle>sd_event_add_time</refentrytitle>
- <manvolnum>3</manvolnum>
- </refmeta>
-
- <refnamediv>
- <refname>sd_event_add_time</refname>
- <refname>sd_event_source_get_time</refname>
- <refname>sd_event_source_set_time</refname>
- <refname>sd_event_source_get_time_accuracy</refname>
- <refname>sd_event_source_set_time_accuracy</refname>
- <refname>sd_event_source_get_time_clock</refname>
-
- <refpurpose>Add a timer event source to an event loop</refpurpose>
- </refnamediv>
-
- <refsynopsisdiv>
- <funcsynopsis>
- <funcsynopsisinfo>#include <systemd/sd-bus.h></funcsynopsisinfo>
-
- <funcprototype>
- <funcdef>int <function>sd_event_add_time</function></funcdef>
- <paramdef>sd_event *<parameter>event</parameter></paramdef>
- <paramdef>sd_event_source **<parameter>source</parameter></paramdef>
- <paramdef>clockid_t <parameter>clock</parameter></paramdef>
- <paramdef>uint64_t <parameter>usec</parameter></paramdef>
- <paramdef>uint64_t <parameter>accuracy</parameter></paramdef>
- <paramdef>sd_event_time_handler_t <parameter>handler</parameter></paramdef>
- <paramdef>void *<parameter>userdata</parameter></paramdef>
- </funcprototype>
-
- <funcprototype>
- <funcdef>typedef int (*<function>sd_event_time_handler_t</function>)</funcdef>
- <paramdef>sd_event_source *<parameter>s</parameter></paramdef>
- <paramdef>uint64_t <parameter>usec</parameter></paramdef>
- <paramdef>void *<parameter>userdata</parameter></paramdef>
- </funcprototype>
-
- <funcprototype>
- <funcdef>int <function>sd_event_source_get_time</function></funcdef>
- <paramdef>sd_event_source *<parameter>source</parameter></paramdef>
- <paramdef>usec_t *<parameter>usec</parameter></paramdef>
- </funcprototype>
-
- <funcprototype>
- <funcdef>int <function>sd_event_source_set_time</function></funcdef>
- <paramdef>sd_event_source *<parameter>source</parameter></paramdef>
- <paramdef>usec_t <parameter>usec</parameter></paramdef>
- </funcprototype>
-
- <funcprototype>
- <funcdef>int <function>sd_event_source_get_time_accuracy</function></funcdef>
- <paramdef>sd_event_source *<parameter>source</parameter></paramdef>
- <paramdef>usec_t *<parameter>usec</parameter></paramdef>
- </funcprototype>
-
- <funcprototype>
- <funcdef>int <function>sd_event_source_set_time_accuracy</function></funcdef>
- <paramdef>sd_event_source *<parameter>source</parameter></paramdef>
- <paramdef>usec_t <parameter>usec</parameter></paramdef>
- </funcprototype>
-
- <funcprototype>
- <funcdef>int <function>sd_event_source_get_time_clock</function></funcdef>
- <paramdef>sd_event_source *<parameter>source</parameter></paramdef>
- <paramdef>clockid_t *<parameter>clock</parameter></paramdef>
- </funcprototype>
-
- </funcsynopsis>
- </refsynopsisdiv>
-
- <refsect1>
- <title>Description</title>
-
- <para><function>sd_event_add_time()</function> adds a new timer
- event source to an event loop object. The event loop is specified
- in <parameter>event</parameter>, the event source is returned in
- the <parameter>source</parameter> parameter. The
- <parameter>clock</parameter> parameter takes a clock identifier,
- one of <constant>CLOCK_REALTIME</constant>,
- <constant>CLOCK_MONOTONIC</constant> and
- <constant>CLOCK_BOOTTIME_ALARM</constant>. See
- <citerefentry><refentrytitle>timerfd_create</refentrytitle><manvolnum>2</manvolnum></citerefentry>
- for details regarding the various types of clocks. The
- <parameter>usec</parameter> parameter takes a time value in
- microseconds, relative to the clock's epoch specifying when the
- timer shall elapse the earliest. The
- <parameter>accuracy</parameter> parameter takes an additional
- accuracy value in microseconds specifying a time the timer event
- may be delayed. Specify 0 for selecting the default accuracy
- (250ms). Specify 1 for most accurate timers. Consider specifying
- 60000000 or larger (1h) for long-running events that may be
- delayed substantially. Picking higher accuracy values allows the
- system to coalesce timer events more aggressively, thus improving
- power efficiency. The <parameter>handler</parameter> shall
- reference a function to call when the timer elapses. The handler
- function will be passed the <parameter>userdata</parameter>
- pointer, which may be chosen freely by the caller. The handler is
- also passed the configured time it was triggered, however it might
- actually have been called at a slightly later time, subject to the
- specified accuracy value, the kernel timer slack (see
- <citerefentry><refentrytitle>prctl</refentrytitle><manvolnum>2</manvolnum></citerefentry>)
- and additional scheduling latencies.</para>
-
- <para>By default, the timer will elapse once
- (<constant>SD_EVENT_ONESHOT</constant>), but this may be changed
- with
- <citerefentry><refentrytitle>sd_event_source_set_enabled</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
- If the handler function returns a negative error code, it will be
- disabled after the invocation, even if
- <constant>SD_EVENT_ON</constant> mode is set.
- </para>
-
- <para><function>sd_event_source_get_time()</function> retrieves
- the configured time value of a timer event source created
- previously with <function>sd_event_add_time()</function>. It takes
- the event source object and a pointer to a variable to store the
- time in microseconds in.</para>
-
- <para><function>sd_event_source_set_time()</function> changes the
- configured time value of a timer event source created previously
- with <function>sd_event_add_time()</function>. It takes the event
- source object and a time relative to the selected clock's
- epoch, in microseconds.</para>
-
- <para><function>sd_event_source_get_time_accuracy()</function>
- retrieves the configured accuracy value of a timer event source
- created previously with <function>sd_event_add_time()</function>. It
- takes the event source object and a pointer to a variable to store
- the accuracy in microseconds in.</para>
-
- <para><function>sd_event_source_set_time_accuracy()</function>
- changes the configured accuracy of a timer event source created
- previously with <function>sd_event_add_time()</function>. It takes
- the event source object and an accuracy, in microseconds.</para>
-
- <para><function>sd_event_source_get_time_clock()</function>
- retrieves the configured clock of a timer event source created
- previously with <function>sd_event_add_time()</function>. It takes
- the event source object and a pointer to a variable to store the
- clock identifier in.</para>
-
- </refsect1>
-
- <refsect1>
- <title>Return Value</title>
-
- <para>On success, these functions return 0 or a positive
- integer. On failure, they return a negative errno-style error
- code. </para>
- </refsect1>
-
- <refsect1>
- <title>Errors</title>
-
- <para>Returned errors may indicate the following problems:</para>
-
- <variablelist>
- <varlistentry>
- <term><constant>-ENOMEM</constant></term>
-
- <listitem><para>Not enough memory to allocate an object.</para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><constant>-EINVAL</constant></term>
-
- <listitem><para>An invalid argument has been passed.</para></listitem>
-
- </varlistentry>
-
- <varlistentry>
- <term><constant>-ESTALE</constant></term>
-
- <listitem><para>The event loop is already terminated.</para></listitem>
-
- </varlistentry>
-
- <varlistentry>
- <term><constant>-ECHILD</constant></term>
-
- <listitem><para>The event loop has been created in a different process.</para></listitem>
-
- </varlistentry>
-
- <varlistentry>
- <term><constant>-EOPNOTSUPP</constant></term>
-
- <listitem><para>The selected clock is not supported by the event loop implementation.</para></listitem>
-
- </varlistentry>
- </variablelist>
- </refsect1>
-
- <refsect1>
- <title>Notes</title>
-
- <para><function>sd_event_add_time()</function> and the other functions
- described here are available as a shared library, which can be
- compiled and linked to with the
- <constant>libsystemd</constant> <citerefentry project='die-net'><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>
- file.</para>
- </refsect1>
-
- <refsect1>
- <title>See Also</title>
-
- <para>
- <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
- <citerefentry><refentrytitle>sd-event</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
- <citerefentry><refentrytitle>sd_event_new</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
- <citerefentry><refentrytitle>sd_event_add_signal</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
- <citerefentry><refentrytitle>sd_event_add_child</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
- <citerefentry><refentrytitle>sd_event_add_defer</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
- <citerefentry><refentrytitle>clock_gettime</refentrytitle><manvolnum>2</manvolnum></citerefentry>,
- <citerefentry><refentrytitle>sd_event_source_set_enabled</refentrytitle><manvolnum>3</manvolnum></citerefentry>
- </para>
- </refsect1>
-
-</refentry>
~ianmdlvl / elogind.git / blobdiff